Shaft Excavation

Summary

Shaft excavation is a specialized vertical excavation technique used to create access points for underground construction projects, ventilation systems, utility connections, and transportation infrastructure.

Conventional Drill and Blast
Uses controlled explosives for hard rock conditions.
Sequence: drilling, charging, blasting, mucking, ground support installation. Requires careful vibration monitoring and blast design.

Mechanical Excavation
- Uses roadheaders, excavators, or specialized shaft boring machines
- Suitable for softer ground conditions.
- Produces less vibration than blasting methods

Raise Boring
- Begins with a pilot hole drilled from surface to underground.
- Reaming head attached underground and pulled upward.
- Creates smooth shaft walls with minimal ground disturbance.

Blind Shaft Sinking
- Excavation proceeds from top to bottom without lower access.
- Materials removed through the shaft opening at the surface.
- Often requires more extensive ground support.

Caisson Method
- Uses pre-constructed concrete rings that sink under their own weight.
- Lower edge has cutting shoe for penetration.
- Additional rings added at the top as sinking progresses.

Shaft excavation requires specialized expertise in geotechnical engineering, excavation techniques, and ground support design to ensure safe and efficient construction of these critical underground access points.